Soundboardcrown

[Ron Nossaman]

>Environment humidity was about 60%, that's normal in Belgium (but after
>reading other mails, I think to high for gluing ribs)  Concerning the
>humidity of the wood it self, I can't tell you.
>
>I made the board and placed it upside down (has to, otherwise you will
>get reversed crown)  in the press for gluing on the ribs. The wood of
>the press bends just enough when you blow the hoses for receiving about
>1 cm of crown
>The strange thing is when I eye-checked it,  the crown seems to have
>disappeared (ie, when the board came out of the press, one really saw
>the crown) .  But now, when I'm heating it to dry before gluing it in
>the piano, and checked it with a straight piece of lumber I have crown
>(about 12, 13 mm) across the ribs, the highest point of the board is
>where it has to be, and I see  a little bit of negative crown along the
>ribs (although this could be caused from heating the board, so it'll be
>warmer in the center as on the ends)

Peter,
 From your description, I wouldn't expect your board to have done anything 
else but go flat when you dried it. Why would you dry it to glue it in the 
piano when you apparently didn't to glue on the ribs? I don't understand. 
As Del said, I hope you can get the ribs off without destroying the panel 
so you can start over again. In the four years or so that you've posted to 
the list, at least a month's worth of reading has been posted on soundboard 
crowning methods and expected results. Please go back and read some of this 
stuff, particularly the differences between rib crowning and panel 
(compression) crowning.

Ron N